Riding lawn mower



FIG. 1 is a front view of a riding lawn mower showing our new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is an upper right perspective view thereof;

FIG. 7 is an enlarged view of a portion of FIG. 5; and,

FIG. 8 is an enlarged view of a portion of FIG. 6.

The broken lines shown in the drawings represent unclaimed environment only and form no part of the claimed design. 

CLAIM The ornamental design for a riding lawn mower, as shown and described. 